CS230 Data Structures, Wellesley College, Fall 1999

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Instructor: Franklyn Turbak (please call me "Lyn")

Office: SCI 121B (behind the Mini-Focus consultant's desk)

Phone: x3049

Email: fturbak@wellesley.edu

Office Hours: Tuesday/Thursday 3:00 -- 5:00; Wednesday 1:30 --3:30. Meetings and seminars sometimes come up during these times, so I will keep you informed each week about any changes in my office hours. For example, on Tuesday, Sep 7, I will be leaving my office at 4:45 in order to attend convocation.

Other Availability: Please feel free to schedule appointments to meet with me outside my normal office hours. I am usually at Boston University all day on Mondays and during the afternoons on Fridays, so it is unlikely to catch me on campus during these times.

Class Times

All classes are held on Tuesdays and Thursdays in SCI E211 from 1:30 to 2:40.


There are two tutors for CS230 this semester: Akuba Dolphyne and Frances Lee. Both have extensive experience with Java, and both took CS111 and CS230 with me the first semesters they were taught in Java.

The drop-in tutor hours are in E101 during the following times:

Akuba and Frances plan to alternate on a weekly basis who takes Tuesday night and who takes Wedesday night.

Some hints on drop-in tutors:

If you need more personalized attention than a drop-in tutors can provide, please consider applying for a one-on-one tutor from the Learning and Teaching Center (LTC) . This service is confidential and free of charge; please take advantage of it if you need some extra help! Contact us or LTC for more information about this service.

Course Overview

CS230 focuses on four "big ideas":

  1. Data Abstraction: In order to cope with the complexity of large writing programs, it is desirable to express them as combinations of components whose behavior can be understood independently from their implementation. In CS111, you learned how methods provide an abstraction barrier between the caller and implementer of a method. We will review this notion and introduce abstract data types (ADTs) as a way of thinking about computational values and the operators that manipulate them.
  2. Modularity: The ability to create complex artifacts (computational or otherwise) is enhanced if they can be composed out of reusable components with standard interfaces that can be combined in mix-and-match ways. We will study how to compose programs out of mix-and-match components.
  3. Algorithmic Complexity: Programs are often judged by how effectively they make use of resources such as space and time. Algorithmic complexity is a tool for analyzing the efficiency of algorithms. We will use this tool to evaluate various approaches to implementing data structures.
  4. Standard Tools: We will learn some classical data structures and algorithms that should be in every programmer's bag of tricks.

These ideas will be explored in the context of a variety of fundamental structures used in Computer Science, including lists, trees, graphs, stacks, queues, priority queues, sets, and tables. We will use Java as the language for describing implementations of these structures.


The prerequisite for CS230 is CS111, Computer Programming and Problem Solving. Students with significant programming experience who have not taken CS111 may take the course with permission of the instructor.


There are two 70-minute lectures each week, which will introduce the main content of the course. Optional review sessions will be scheduled during the semester as the need arises.


Required Text: The text we will be using this semester is Java Structures: Data Structures in Java for the Principled Programmer, by Duane A. Bailey. The text is available at the bookstore. We will not follow the text closely, but it is a good reference.

Lecture Notes: Some of the material presented in lecture will be summarized in lecture notes accessible from this web site. However, there will be no lecture notes for much of the material presented in class. Students are expected to attend all lectures and take their own notes of material covered in lecture.

E101 Library: The CS department has purchased a collection of books relevant to CS230, CS111, and CS110 that will be kept in the bookshelves near the front door of E101. A copy of the required text may also be found there. See the E101 library page for a listing of the holdings and the rules for borrowing from the collection.

Science Center Library: A number of Java programming books are on reserve in the Science Center. You may borrow them for use within the library.



There will be weekly or bi-weekly assignments in which you will write Java programs that emphasize concepts discussed in class.

Many of the assignments will be challenging. Keep in mind that programming often consumes more time than you think it will. Start your assignments early! This will give you time to think about the problems and ask questions if you hit an impasse. Waiting until the last minute to begin an assignment is a recipe for disaster.

All assignments are due in class on the advertised due date, which will typically be a Thursday. You should turn in both a "hard" (paper) copy of your assignment and a "soft" (electronic) copy of any programs from the assignment. Soft copies should be submitted to the drop folder for assignments, which can be found in the CS230 folder on cs230.wellesley.edu. A soft copy submission will typically be a folder containing your programs and any other information you think is appropriate. Be sure that the name of this folder includes both your name and the assignment number.

Assignments will be graded on a 100 point scale. I will try to have assignments graded as soon as possible. Solutions to assignments will be posted on the web.

Make backups of all your floppy disks regularly throughout the term! Numerous students have lost all of their work when they could least afford it. Don't join them!

Problem Set Header Sheets

I would like to get a sense for how much time it takes you to do your CS230 problem sets. Please keep track of the time you spend on each problem of your problem sets, and include this information on the problem set header sheets that will be provided for each problem set. Turn in this header sheet as the first page of your hardcopy solutions.

Late Problem Set Policy

I realize that it is not always possible to turn in problem sets on time. On the other hand, turning in one problem set late can make it more difficult to turn in the next problem set on time. I have decided on the following policy for this course this term:

A problem set due on a particular day will be accepted until 11:59pm of that day without penalty. A problem set can be turned in n days late if it is accompanied by n Lateness Coupons.

At the beginning of the term, you will receive a sheet with ten Lateness Coupons that you can use throughout the term. Use them wisely: you only get ten, and they are not copyable or transferable between students. Lateness Coupons can only be used on problem sets; they cannot be used on exams.

You may turn in late problem sets by slipping them under my office door. Of course, if I hand out solutions before you turn in a late problem set, you are bound by the Honor Code not to examine these solutions.

In extenuating circumstances (e.g.,, sickness, personal crisis, family problems), you may request an extension without penalty. Such extensions are more likely to be granted if there are madev before the due date.

Collaboration Policy

I believe that collaboration fosters a healthy and enjoyable educational environment. For this reason, I encourage you to talk with other students about the course and to form study groups. Unless otherwise instructed, feel free to discuss assignments with other students and exchange ideas about how to solve the problems. However, there is a thin line between collaboration and plagiarizing the work of others. Therefore, unless otherwise instructed, you must compose your own solution to each assignment. In particular, while you may discuss strategies for approaching the programming assignments with your classmates and may receive debugging help from them, you are required to write all of your own code. In general, it is unacceptable (1) to write a program together and turn in two copies of the same program or (2) to copy code written by your classmates. However, it is OK to borrow code from the textbooks, from materials discussed in class, and from other sources as long as you give proper credit.

In keeping with the standards of the scientific community, you must give credit where credit is due. If you make use of an idea that was developed by (or jointly with) others, please reference them appropriately in your work, e.g., if person X gets a key idea for solving a problem from person Y, person X's solution should begin with a note that says "I worked with Y on this problem" and should say "The main idea (due to Y) is ...'' in the appropriate places. It is unacceptable for students to work together but not to acknowledge each other in their write-ups.

When working on assignment problems, it is perfectly reasonable to consult public literature (books, articles, etc.) for hints, techniques, and even solutions. However, you must reference any sources that contribute to your solution. Assignments and solutions from previous terms of CS230 are not considered part of the "public'' literature. You must refrain from looking at any solutions from previous terms of CS230. It is my policy that consulting assignment solutions from previous terms constitutes a violation of the Honor Code.


There will be three CS230 exams, all open book and open notes:

  1. A take-home exam that will be posted on Wednesday, October 13 and will be due by 11:59pm on Wednesday, October 20. The take-home exam will require use of a computer. You are not allowed to collaborate with anyone else on the take home exam.
  2. A take-home exam that will be handed out on Thursday, November 11 and will be due by 11:59pm on Thursday, November 18. The take-home exam will require use of a computer. You are not allowed to collaborate with anyone else on the take home exam.
  3. A final exam during the regular exam period.

Please mark these dates in your calendars. If you have any conflicts regarding the exam dates, you must contact your instructor as soon as possible.


Grading Policy

The final grade in the class will be computed as a weighted average of several components. The relative weight of the each component is shown below:

Assignments (total)


Exam 1 (take-home)


Exam 2 (take-home)






All assignments are weighted equally. Assignments account for the largest percentage of the grade. If you do not do these assignments, you will not pass the course!

Students often like to know how I assign final letter grades for the course based on the numerical average that you earn. What I usually do is: >= 93.33 is an A, >= 90.00 is an A-, >= 86.67 is a B+, >= 83.33 is a B, >= 80.00 is a B-. >= 76.67 is a C+, >= 73.33 is a C, >= 70.00 is a C-, >= 60.00 is a D and < 60.00 is an F. Note - I may certainly curve this such that you earn an A with a grade lower than a 93.33 (for example). This decision will be based on the overall performance of the class. I will never curve in the opposite direction.


CS230 software can be run on all Macintoshes on campus, although you may need to install some additional software yourself; see Software Installation for more details.

This semester we will be programming in the Symantec Cafe Java development environment for the Macintosh. Although there is a PC version of the Symantec Cafe Java development environment, we do not officially support the PC version due to a lack of staffing and experience. Nevertheless, if you have the burning desire to use Symantec Cafe on your PC, you can ask us for some pointers on how to acquire, install, and use the PC version. We would be delighted if a student or set of students would learn enough about the PC version of Symantec Cafe to become local experts willing to help other students in this regard.

This is the last semester we plan to use Symantec Cafe in CS230. In Spring of 2000, we plan to switch to Metrowerks Code Warrior and fully support both Mac and PC versions. At that time we will also switch to a more current version of Java. (We are currently using Java 1.0.2, which is "ancient" as far as these things go.)

Throughout the course, you will need to use standard applications like Netscape, Fetch, email, and FirstClass. The Documentation has pointers to documentation for all the software packages used in CS230.

Each CS230 student will be given a password-protected account on the CS230 file server (cs230.wellesley.edu). You will have a limited amount of space on the CS230 server to store your course-related files.

You are also expected to keep copies of all your course work on floppy disks or zip disks. Removable disks are a frail medium that you should handle carefully.Store and transport them in suitable protected containers. Do not subject them to temperature extremes, put them near magnetic fields, store them unprotected in your pockets, etc. Even if you handle floppy and zip disks carefully, they are still prone to failure. For this reason, you should regularly back up your floppy or zip disks!

Every time you insert a floppy disk into a computer, you may be transmitting a computer virus! Viruses are nasty software fragments that can erase information on your computer or cause other malfunctioning. In order to reduce the spread of computer viruses, make sure that any personal computers you use have appropriate virus protection software installed.

While planning your computer usage, keep in mind that computers do break down and Wellesley's are no exception.

Course Directory

The CS230 course folder is located on cs230.wellesley.edu in the same directory as all the CS230 student accounts. This directory contains material relevant to the class, including course software, and on-line versions of assignments and programs. From Netscape, all this information is available via links from the document you are currently reading:


From Fetch or Winsock-FTP, the CS230 directory can be accessed by connecting to cs230.wellesley.edu and navigating to /usr/users/cs230.

Course Folder on FirstClass

There is a CS230 folder on FirstClass. This class folder has several purposes. I will use it to make class announcements, such as corrections to assignments and clarifications of material discussed in class. I encourage you to post questions or comments that are of general interest to the course. I and the tutors will all read the folder on a regular basis and post answers to questions found there. The course folder is also a good place to find people to join a study group. You should plan on reading this folder on a regular basis.

Announcements concerning the course will be posted on the CS230 home page. You should check this page regularly for important course information.

Finding Help

If you have any questions at all about the class (whether big or small, whether on assignments, lectures, reading, or whatever) please contact me. That's what I'm here for!

Simple questions can often be answered via the class folder or email. Questions of general interest (e.g. clarifying ambiguities in an assignment, wondering why posted programs do not work as expected) should be posted to the CS230 class folder. Other questions can be addressed to me at fturbak@wellesley.edu.

If you have a complex question or need help in understanding the material, you are encouraged to see me or a CS230 tutor. The best time to see me in person is during my office hours (listed at the top of this document). If these times are not convenient, we can schedule an appointment for some other time. You can schedule an appointment in person, via phone, or via email.

Drop-in tutors are available to answer your questions during certain hours. The names and schedules of the drop-in tutors will be made available early in the term. If you are having trouble with the course, you can request a one-on-one tutor from the Learning and Teaching Center (LTC) This service is confidential and free of charge; please take advantage of it if you need some extra help! Contact us or LTC for more information about this service.

Finally, when looking for help, do not overlook other students --- not only those who have taken the course in the past, but your classmates as well. Get to know your classmates early in the term so that you can help each other out!


We are eager to hear your feedback on CS230! You can talk to the instructor or tutors in person, send email to us, or post a message in the CS230 class folder.

Students with Special Needs

If you have any disabilities (including "hidden" ones, like learning disabilities), you are encouraged to meet with me to discuss accommodations that may be helpful to you.

Mathematical Modeling Distribution

CS230 counts for one Mathematical Modeling (MM) distribution credit.